We reviewed the records of 70 patients who underwent resection of a carcinoma of the colon and rectum with en bloc total cystectomy (36 patients) or partial cystectomy (34 patients) because of tumor directly extending into the urinary bladder. Preoperative genitourinary symptoms were present in 33 of the 70 patients (41.7 percent) and were highly predictive of malignant invasion of the bladder (97.0 percent). Duration of catheter drainage after partial cystectomy correlated with early postoperative bladder function; all 25 patients who had the catheter remain in place at least ten days had normal voiding after catheter removal, while five of nine patients whose catheter was removed before ten days had retention requiring catheter reinsertion (p < 0.01). Urologic complications occurred in two patients after total cystectomy and in three patients after partial cystectomy. There were three postoperative deaths in the total cystectomy group but none after partial cystectomy. Sixty-four patients with negative resection margins had a median survival period of 34 months and a five-year actuarial survival rate of 51.8 percent. In contrast, the median survival period for six patients who had positive margins was 11 months, with no survivors at five years.